Method of desulfurizing and decopperizing ferrous metal



Patented June 20, 1950 METHOD OF DESULFURIZING AND DECOPPERIZING FERROUSMETAL James Fernando Jordan, Huntington Park, Calif.

N0 Drawing- Application May 26, 1949, Serial No. 95,591

4 Claims. (01475-53) g l My invention relates to the desulphurizationand decopperization of molten ferrous metals.

This is a continuation-in-part of my copending application Serial No.26,937, filed on May 13,

1948, and-my copending application Serial No.

49,217, filed on Sept. 14, 1948, both now abandoned;

The copper content of the steel being produced in the United States hasbeen slowly gaining ground, as the result of the copper content of pigiron and the influx of copper-bearing metals into the steel-scrapportion of the typical steel-making charge. While a certain measure ofcopper is supposed to help the corrosion resistance of steel,

there are other effects of copper in steel which are bad. Thus, forexample, copper harms the deep-drawing properties of steel. I

I have found a reagent slag that is capable of extracting copper andsulphur from molten iron or molten steel. My reagent slag contains, asits principal desulphurizing and decopperizing agent, either sodiumsulphide, or potassium sulphide, or aluminum sulphide.

In my copending application, Serial No. 26,937,

I disclosed my reagent slag for desulphurizing molten iron, said slagcontaining either sodium sulphide, or potassium sulphide, or aluminumsulphide as its principal desulphurizing agent. I have found that whensufiicient sulphur is present in the ferrous metal to convert the coppercontent of said metal to cuprous sulphide, my previously-discloseddesulphurizing slag will also decopperize said ferrous metal.

While my discovery, indicates that copper has a greater afiinity forsulphur than iron has at those temperatures where ferrous metals aremolten, other commonly-employed alloying constituents in said ferrousmetals have a still greater afiinity for sulphur. Thus, for example,manganese and aluminum both have a greater afiinity for sulphur thancopper has. As a consequence in the presence of such elements assaidmanganese and/or aluminum, copper will not combine with the sulphurcontent of the ferrous metal until sufiicient sulphur is present tofirst satisfy the conversion requirements of said manganese and/oraluminum.

My practice in treating ferrous metal is to assume that the sulphurrequirements of copper may be estimated by multiplying the coppercontent of the metal by 0.28; that the sulphur requirements of themanganese may be estimated by multiplying the manganese content of themetal by 0.64.; and that the sulphur requirements of the aluminum may beestimated by multiplying the aluminum content of the metal by 1.9. Ingeneral, the copper and manganese factors are about 10% abovethe assumedequation requirements; the aluminum factor being satisfactory in thepresence of the usually small aluminum content-of ferrous metal.

for example, in a test that I made with an iron containing 3.34% carbon,2.10% silicon, 0.10%manganese, and 0.30% copper, I added 0.155% sulphur.Contact with molten sodium sulphide at..2500 F. lowered these values to0.009% manganese, 0.04% copper, and 0.019% sulphur. This sodium sulphidereagent contained 20% aluminum sulphide.

In another case, I treated a molten iron contaming 4.35% carbon, 3.34%silicon, 0.89% manganese, and 0.25% copper, with a 0.65% sulphuraddition. Contact with a molten sodium-aluminum sulphide lowered thesevalues to 0.05% manganese, 0.03% copper, and 0.027% sulphur.

Deoxldized steel may be treated with sulphide slag to remove copperandsulphur therefrom. In a test that I made with a steel containing0.30% carbon, 0.41% silicon, 0.17% manganese, and 0.76% copper, I added0.35% sulphur. Contact with molten sulphide slag containing aluminumsulphide. and 10% aluminum oxide lowered these valuesto 0.02% manganese,0.05% copper, and 0.020% sulphur. In another test that I made with thissteel, I added enough aluminum to the steel to yield a residual aluminumcontent of 0.05%, and then I treated the resulting metal with 0.43%sulphur. Contact with the molten aluminum sulphide aluminum oxidereagent gave 0.02% manganese, 0.07% copper, and 0.011% sulphur. I,

These molten sulphide slags must be protected fromv the air, for saidsulphides show a marked tendency to oxidize to the corresponding sulphates. Furthermore, fume hoods are a required accessory in my process,although I have had good success in depressing the fuming of the moltensulphides by elevating their boiling points by means of thenon-volatile-solute effect. Thus, I depressed the fuming of sodiumsulphide by adding aluminum sulphide thereto, and I depressed the fumingof aluminum sulphide by adding aluminum oxide thereto.

If, in addition to, or in place of, manganese and/or aluminum, theferrous metal contains other elements which have a greater afiinity forsulphur than has copper, then sufiicient sulphur must be added to themetal to convert these other elements into their correspondingsulphides; for,

copper will not combine with sulphur in the pres-- sults with a slagcomposed of 60% potassium.

and 40% aluminum sulphide, and I have obtained good results with a slagcomposedi ofiT30,%L po-r tassium sulphide, 30% sodium sulphide,and 40%aluminum sulphide.

by my sulphide slag is apparently favored by 1947, now abandoned; SerialNo. 69,467, filed on Jan. 6, 1949; and Serial No. 73,993, filed on Feb.1, 1949-the latter two counter-current extractors being most suitablefor use in an extraction process wherein intimate contact between thesolvents and the absence of air are desirable, such as in the presentcase.

Having now described several forms of" my invention, I wish it to beunderstood that my invention is not to be limited to the specific formor arrangement of steps herein disclosed, except 1 insofar as suchlimitations are specified in the aphigher extraction temperatures.

In several tests that I made, the nickel content.

of the molten ferrous metal was observed to have partly passed into thesulphide slag with the cop: per; and in certain other tests made at verylow extraction temperatures, the: molybdenum" eon tentof, themetalpassed, in part, into the sulphide slag with the copper. g 3

The factor which I use to figuretheproper concentration of sulphur inaferrous metal tob'e treated for, the removal of its copper content aremy preferred embodiment; however'j l have ob} tained a certain measure fdecopperizationwith lower sulphur.percentages -thus;. in a test thatImade with the" molten iron that'contained 323 3 75 carbon, 1'added'-0;099'% sulphur. Contactwith the molten sodium sulphide-aluminumsulphide slag gave the .following' results: ;009%"manganese, 0.22%copper, and" 0.012% sulphur.

The emimerated: tests employed one pound of slagf-or every pound ofmetal, treated-*whenithe sulphur content of the metaiwasbelow 0.25%; andsaid, tests employed every pound of metaljtreated when the metalcontained more than 0.25% sulphur The efi'iciency of my process maybe;reatly increased by, recovering the copperamanganese bearing waste slag;This .may ing. saidwaste slag, while it'is molten, with aluminum,whereupon, said alummumwill displace the copper and, manganesethereinlyielding an alloy of copper and manganese, and alum nu sulphide.V

The efliciency of the extraction may-be greatly increased by employing acounter current extractor--this in keepingr with the well knownincreased efiiciency derived from employing the counter-currentprinciple in extraction processes. Counter-current extractorssuitable-for use-'in extracting sulphur and copper from molten ferrousmetals are disclosed'inmy' copending applications: Serial No.783,391,.fi1eddn- O ctj 3-1,

two pounds; of: slag for I be done by treat- 1 pended claims.

' I claim as my invention:

1. The method of refining iron and steel containing: copper, whichcomprises: melting the copper-bearing metal; adding suificient sulphurto the-molten metal to convert into their respective sulphides anymetals present in said molten metal having a greater affinity forsulphur than the affinity of copper for sulphura-nd'to convert asubstantial portionof theoopper present into cuprous sulphide;contacting; said molten metal witha: molten sulphide slag consistingessentially of a sulphide selected from the group consisting of sodiumsulphide, potassium sulphide, aluminum sulphide, and mixtures thereof;and separating said slag from saidmetal after said molten sulphide slaghas lowered the copper content of said molten metal and after said;molten sulphide slaghas extracted from said molten metal a substantialportion of the sulphur that was added to said moltenmetal.

2. The process according toclaim I in which said molten sulphide slagconsists essentially of sodium sulphide.

3. The process according toclaim 1' in which said molten sulphide slagconsists essentially of potassium sulphide.

4:. The process according toclaim 1 in which said molten sulphide slagconsists essentially of aluminum sulphide.

JAMES FERNANDO JORDAN;

REFERENCES CITED' The following references are of record in th file ofthis patent:

UNITED STATES PATENTS Number Name Date 838,125 Maffett Dec. 11, 19061,425,701 Sem Aug; 15,1922 1,785,503 Spring Dec.. 16 1930 1,837,432I-Ianak Dec. 22 .1931 1,982,959 Kuhlmann Dec. 4,, 1934 2,109,144Betterton Feb, 22, 1938 2,301,360 Brennan Nov. 10, 1942

1. THE METHOD OF REFINING IRON AND STEEL CONTAINING COPPER, WHICH COMPRISES: MELTING THE COPPER-BEARING METAL; ADDING SUFFICIENT SULPHUR TO THE MOLTEN METAL TO CONVERT INTO THEIR RESPECTIVE SULPHIDES ANY METALS PRESENT IN SAID MOLTEN METAL HAVING A GREATER AFFINITY FOR SULPHUR THAN THE AFFINITY OF COPPER FOR SULPHUR AND TO CONVERT A SUBSTANTIAL PORTION OF THE COPPER PRESENT INTO CUPROUS SULPHIDE; CONTACTING SAID MOLTEN METAL WITH A MOLTEN SULPHIDE SLAGE CONSISTING ESSENTIALLY OF A SULPHIDE SELECTED FROM THE GROUP CONSISTING OF SODIUM SULPHIDE, POTASSIUM SULPHIDE, ALUMINUM SULPHIDE, AND MIXTURES THEREOF; AND SEPARATING SAID SLAG FROM SAID METAL AFTER SAID MOLTEN SULPHIDE SLAG HAS LOWERED THE COPPER CONTENT OF SAID MOLTEN METAL AND AFTER SAID MOLTEN SULPHIDE SLAG HAS EXTRACTED FROM SAID MOLTEN METAL A SUBSTANTIAL PORTION OF THE SULPHUR THAT WAS ADDED TO SAID MOLTEN METAL. 